Concatenated channel encoding that uses, for example, Reed-Solomon code as external code and, for example, convolutional code as internal code, is conventionally applied as an error correction encoding process for the digital terrestrial broadcasting. A receiving apparatus thereof executes an error correction process that combines, for example, Viterbi decoding and Reed-Solomon decoding. An iterative decoding approach is proposed that improves the error correction capacity by repeating the error correction process executed by the receiving apparatus multiple times (see, e.g., Japanese Laid-Open Patent Publication No. 2011-205511; Lamarca, Meritxell, et al, “Iterative Decoding Algorithms for RS-Convolutional Concatenated Codes”, Proc. of 3rd intl. Symposium on Turbo Codes and Related Topics (2003); and Murata, Shinichi, et al, “An Iterative-Decoding Method for Concatenated Error-Correcting Codes on ISDB-T”, General Meeting of Institute of Electronics, Information and Communication Engineers, B-5-156, March 2008).
According to the technique disclosed in the literature of Lamarca, M., et al a soft decision output scheme such as soft output Viterbi algorithm (SOVA) decoding or Max-log-MAP decoding is used for a decoding process supporting the convolutional code. Similarly, the soft decision output scheme is employed in the Reed-Solomon decoding. On the other hand, according to the technique disclosed in the literature of Murata, S., et al, a feedback value from a Reed-Solomon decoding process to a decoding process supporting the convolutional code is generated depending on the success or failure of the error correction, for each transport stream packet (TSP) that is the processing unit of the Reed-Solomon code.
A method is present according to which a penalty is set depending on the success or failure of the error correction in a Reed-Solomon decoding process and the penalty is fed back to a decoding process supporting the convolutional code. According to this method, a heavy penalty is imposed on the decoding process supporting the convolutional code, when the result of the decoding process does not match the decoded data acquired after the error correction for the TSP for which error correction has been successfully executed (see, e.g., Japanese Laid-Open Patent Publication No. 2011-205511).
However, according to the conventional method of imposing a penalty on the decoding process supporting the convolutional code, reliability can not be determined for the result of the decoding process supporting the convolutional code for a TSP for which error correction has failed. Therefore, a penalty that reflects the reliability of the result of the decoding process cannot be imposed on the decoding process supporting the convolutional code. Therefore, when errors occur in bursts in the decoding process supporting the convolutional code, the error correction fails in the Reed-Solomon decoding process. Therefore, a problem arises in that the correction capacity of the decoding process supporting the convolutional code is degraded.